#include<stdio.h>
int main()
{
  long long hh,mm,ss;
  long long c1,c2,s;
  scanf("%lld%lld",&c1,&c2);
  s=(c2-c1)/100.0+0.5;
  hh=s/3600;
  s=s%3600;
  mm=s/60;
  s=s%60;
  ss=s;
  printf("%02lld:%02lld:%02lld\n",hh,mm,ss);
  return 0;
}